Sorry, giving a usless answer, its not on the website as you say, Ive looked on uktv food, but the recipe seemed very simple if you find a shortbread recipe. She divided the dough in half, flattened one half in an oblong tray with a piece of cling filmover the top to stop it sticking to her hands, spread on the mincemeat and then spread the other half of the dough on top, bake until the shortbread is cooked.
The BBC can't put recipes from 'Rachel's Favourite Food' on the website because of copyright restrictions. However, there is a book to accompany the series, which is available at all good bookshops, which should include the recipe you want and loads of others:
Rachel's Favourite Food by Rachel Allen �19.99 ISBN: 0717138984